Image composition is an important tool for digital image editing. Applications include cutting and pasting selected objects from one image to another and background replacement for selected objects, using such techniques as Poisson editing. For Poisson image editing to work satisfactorily, the user must carefully trace an accurate boundary exactly outlining the source object, so that salient structures in source and target images do not conflict with each other along the pasting boundary. Then, by solving Poisson equations using the user-specified boundary condition, Poisson image editing seamlessly blends the colors from both images, hopefully without visible discontinuities near the boundary.
The effectiveness of Poisson image editing, however, depends on how carefully the user draws the boundary outlining the object to be pasted. Thus, Poisson image editing may not always produce good results. If the outline of the object is only casually drawn by the user, the Poisson image editing may generate unnatural blurring artifacts at places where the boundary intersects with salient structures in the target image. What is needed is a way to obtain seamless composition even when the user only casually designates the general region that contains the object to be pasted.